[CostModel] Return an invalid cost for memory ops with unsupported types

Fixes getTypeConversion to return `TypeScalarizeScalableVector` when a scalable vector
type cannot be legalized by widening/splitting. When this is the method of legalization
found, getTypeLegalizationCost will return an Invalid cost.

The getMemoryOpCost, getMaskedMemoryOpCost & getGatherScatterOpCost functions already call
getTypeLegalizationCost and will now also return an Invalid cost for unsupported types.

Reviewed By: sdesmalen, david-arm

Differential Revision: https://reviews.llvm.org/D102515

1 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index f4e3fad..d2c291f 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -1016,8 +1016,8 @@ TargetLoweringBase::getTypeConversion(LLVMContext &Context, EVT VT) const {
     // If type is to be expanded, split the vector.
     //  <4 x i140> -> <2 x i140>
     if (LK.first == TypeExpandInteger) {
-      if (VT.getVectorElementCount() == ElementCount::getScalable(1))
-        report_fatal_error("Cannot legalize this scalable vector");
+      if (VT.getVectorElementCount().isScalable())
+        return LegalizeKind(TypeScalarizeScalableVector, EltVT);
       return LegalizeKind(TypeSplitVector,
                           VT.getHalfNumVectorElementsVT(Context));
     }
@@ -1080,7 +1080,7 @@ TargetLoweringBase::getTypeConversion(LLVMContext &Context, EVT VT) const {
   }
 
   if (VT.getVectorElementCount() == ElementCount::getScalable(1))
-    report_fatal_error("Cannot legalize this vector");
+    return LegalizeKind(TypeScalarizeScalableVector, EltVT);
 
   // Vectors with illegal element types are expanded.
   EVT NVT = EVT::getVectorVT(Context, EltVT,
@@ -1845,6 +1845,9 @@ TargetLoweringBase::getTypeLegalizationCost(const DataLayout &DL,
   while (true) {
     LegalizeKind LK = getTypeConversion(C, MTy);
 
+    if (LK.first == TypeScalarizeScalableVector)
+      return std::make_pair(InstructionCost::getInvalid(), MVT::getVT(Ty));
+
     if (LK.first == TypeLegal)
       return std::make_pair(Cost, MTy.getSimpleVT());